The Differences Between Matter and Anti Matter

How do you know if something is matter or anti matter? It's a great question. We have to think about like the differences between matter and anti matter. What is the difference? why do both of them exist? Is it really totally symmetric? And we know of course the answer is that it's not totally symmetric. There are some processes out there that seem to prefer making matter instead of anti matter, but we still don't understand it.